SR OS supports PBB-EVPN E-Tree services in accordance with IETF RFC 8317. PBB-EVPN E-Tree services are modeled as PBB-EVPN services where some I-VPLS services are configured as etree and some of their SAP or spoke SDPs are configured as leaf-acs.
The procedures for the PBB-EVPN E-Tree are similar to those for the EVPN E-Tree, except that the egress leaf-to-leaf filtering for BUM traffic is based on the B-MAC source address. Also, the leaf label and the EVPN AD routes are not used.
The PBB-EVPN E-Tree operation is as follows.
When one or more I-VPLS E-Tree services are linked to a B-VPLS, the leaf backbone source MAC address (leaf-source-bmac parameter) is used for leaf-originated traffic in addition to the source B-VPLS MAC address (source-bmac parameter) that is used for sourcing root traffic.
The leaf backbone source MAC address for PBB must be configured using the command config>service>pbb>leaf-source-bmac ieee-address before the configuration of any I-VPLS E-Tree service.
The leaf-source-bmac address is advertised in a B-MAC route with a leaf indication.
Known unicast filtering occurs at the ingress PE. When a frame enters an I-VPLS leaf-ac, a MAC lookup is performed. If the C-MAC DA is associated with a leaf B-MAC, the frame is dropped.
Leaf-to-leaf BUM traffic filtering occurs at the egress PE. When flooding BUM traffic with the B-MAC SA matching a leaf B-MAC, the egress PE skips the I-VPLS leaf-acs.
The following CLI example shows an I-VPLS E-Tree service that uses PBB-EVPN E-Tree. The leaf-source-bmac address must be configured before the configuration of the I-VPLS E-Tree. As is the case in regular E-Tree services, SAP and spoke SDPs that are not explicitly configured as leaf-acs are considered root-ac objects.
A:PE-2>config>service# info
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pbb
leaf-source-bmac 00:00:00:00:00:22
exit
vpls 1000 customer 1 name "vpls1000" b-vpls create
service-mtu 2000
bgp
exit
bgp-evpn
evi 1000
exit
mpls bgp 1
ingress-replication-bum-label
auto-bind-tunnel
resolution any
exit
no shutdown
exit
exit
stp
shutdown
exit
no shutdown
exit
vpls 1001 customer 1 i-vpls etree create
pbb
backbone-vpls 1000
exit
exit
stp
shutdown
exit
sap 1/1/1:1001 leaf-ac create
no shutdown
exit
sap 1/1/1:1002 create
no shutdown
exit
no shutdown
exit
The following considerations apply to PBB-EVPN E-Trees and multihoming.
All-active multihoming is not supported on leaf-ac I-VPLS SAPs.
Single-active multihoming is supported on leaf-ac I-VPLS SAPs and spoke SDPs.
ISID- and RFC 7623-based C-MAC flush are supported in addition to PBB-EVPN E-Tree services and single-active multihoming.